1. Field of the Invention
Embodiments of the invention relate to the field of semiconductor, and more specifically, to thermal sensing.
2. Description of Related Art
Thermal design in semiconductor devices has many challenging problems. It is desirable to sense hot areas in a semiconductor die so that appropriate actions may be taken to prevent damages or performance degradation to the die or the system.
Existing techniques for thermal sensing have a number of drawbacks. A common technique is to place a thermal sensor as close as possible to the most active unit or area in the semiconductor die. This technique requires real estate on the die to accommodate the thermal sensing circuit and the availability of a low-noise analog power supply. If the sensor is not located close enough to the actual hot spot, inaccurate thermal sensing may result. In addition, if an analog supply is not available in the vicinity of the sensing circuit, a digital supply has to be used. Using a digital supply may lead to further sensing errors because the digital supply tends to be noisy and may not be accurate due to temperature and process variations. Existing techniques therefore may not adequately provide thermal sensing at multiple locations because of the above problems. Furthermore, the problem of self-heating error introduced during a high volume manufacturing (HVM) trimming has not been adequately addressed.